The Upper Belle Fourche Watershed, located in northeastern Wyoming and western South Dakota, covers approximately 1,083 square miles. The watershed is characterized by a mix of grasslands, forests, and agricultural lands. Snowpack is an important component of the hydrology, with the majority of the annual water supply coming from snowmelt. The watershed is home to several small lakes and reservoirs, including Pactola Reservoir, which provides drinking water to the Rapid City area. Reservoir constituents include sediment, nutrients, and dissolved metals, which can impact water quality. The watershed experiences a semi-arid climate, with precipitation averaging around 20 inches per year. Summers are hot and dry, and winters are cold with frequent snow. Climate change is expected to result in increased temperature and variability in precipitation, potentially impacting water availability and quality in the watershed.